Transformer with wire end insulation means



R. A. ELVERS TRANSFORMER WITH WIRE END INSULATION MEANS Oct. 22, 1968 Filed June 5, 1967 H M w ATTORNEY United States Patent 3,407,372 TRANSFORMER WITH WIRE END INSULATION MEANS Ralph A. Elvers, 5482 Asllurst St.,

Indianapolis, Ind. 46220 Filed June 5, 1967, Ser. No. 643,529 Claims. (Cl. 336-408) ABSTRACT OF THE DISCLOSURE A transformer having an insulator member formed as a generally C-shaped sheet piece which snaps over the winding tube of the transformer, providing an insulating wall, behind which the radially-extending end portions of a wire winding may be passed. Thus those wire-ends, are kept insulated from any portion of another winding of the transformer.

This invention relates to electrical transformers, and more particularly, to means for insulating portions of certain windings from certain other windings of a transformer.

The insulator, having a generally C-shape, is adapted to snap over the winding hub or tube of the transformer; and thus it is held snugly thereon during subsequent processing, adjacent one of the transformer end flanges, by the slight resilient deformation achieved by the tight fit between the insulator and the winding tube and wire.

The end-portions of one of the transformer windings, being passed behind the insulator, are thus economically and effectively insulated from the adjacent winding or windings of the transformer, throughout subsequent processing and use of the transformer. These radially-extending end-portions of the winding, in contrast to the cylindrical turns of the wire, are relatively diflicult to effectively insulate by other methods. For example, a tape strip over those end-portions may get pulled ofl? during subsequent winding processes; and a painted insulation is relatively expensive and diflicult to apply in a manner to withstand the subsequent winding processes. A spaghettitype insulation is bulky and is otherwise disadvantageous.

More specific details and concepts of the invention are set forth in the following more detailed description of an illustrative embodiment of the transformer embodying the novel and advantageous insulation means, taken in conjunction with the accompanying somewhat diagrammatic and schematic drawings, in which:

FIG. 1 is a cross-sectional view of a two-Winding bobbin-type transformer, embodying an insulation means of the present invention, this view being generally as indicated by section-line 11 of FIG. 2;

FIG. 2 is an end view of the transformer shown in FIG. 1;

FIG. 3 is an elevational view of the insulator shown in FIGS 1 and 2; and

FIG. 4 is a detail'view of a portion of FIG. 1, illustrating details of assembly.

As shown in the drawings, the invention, is a transformer 10, herein shown as a bobbin-type, in which an insulator member 12 is carried on the hollow winding tube 14 adjacent one of the transformer end-flanges 16.

The insulator member 12 is formed from thin or sheet material such as Mylar-coated paper, plastic sheet, or thin fibre-board, the material being fairly rigid and having desirably high dielectric, insulating character.

The insulator 12 has a central opening 18, and one side of the insulator 12 is open as at the throat portion 20, the overall insulator 12 being of a general C-shape having three arms 22 which snugly fit onto the transformer "ice winding tube 14. Assisting in maintaining the insulator 12 on the winding tube 14, the edges of the arms 22 adjacent the throat 20 are extended a short distance toward one another, forming shallow fingers 24, they being separated a distance slightly less than the operative diameter of the winding tube 14.

Although fairly rigid, the insulator 12 is flexible and resilient enough to permit its two arms 22 adjacent the open throat 20 to be spread sufficiently that the insulator 12 may be snapped onto the winding tube 14.

The end-portions 26 of the wire of the first or primary winding 28 are passed through the throat 20 and passed under and past the edge 18 of the insulator 12, to the space behind (to the right, in FIG. 1) the insulator 12; and they then radially extend outwardly of the transformer in the space between the insulator 12 and the adjacent end-flange 16. The insulator.12 thus provides a protective flange or wall for the wire-portions 26, protecting those wires 26 for an extent radially at least as far as the outer diameter of the outer windings yet to be applied.

As illustrated in FIG. 4, when the wire-ends 26 are pulled tight, they are drawn under one of the insulator arms 22; and those intermediate portions 29 of the wires (which are thus between the insulator 12 and the winding tube 14) make even more snug the fit 0f the insulator 12 onto the winding tube 14, and are retained by that snug fit.

FIG. 4 also illustrates a Winding technique wherein the wire-ends 26 are passed operatively under and past the insulator, as above described, but without crossing as indicated in FIG. 1.

A cylindrical insulation ring such as a suitable tape strip formed into a cylindrical band 30 is provided, overlying the winding 28. (In contrast to the problem of keeping the end-portions 26 of winding 28 insulated from other windings, the cylindrically-formed winding 28 is rather effectively insulated from an outer winding by the relatively easy and economical tape layer 30; for the subsequent winding operation does not readily tear off the insulation provided by the cylindrical layer 30. That is, a cylindrical insulation layer 30 is not only easy to apply, but the subsequent winding process is not as likely to tear it ofi than some sort of tape layer which attempts to insulate the radially-extending wire-portions protected in this invention by the insulator 12. Moreover, the subsequent winding tends to hold the cylindrical insulation layer 30 in place.)

The insulation layer 30, it will 'be observed, extends clear over to the insulator 12, with relatively little expense in extending it that far; and the junction of that layer 30 with the insulator 12 at locations 31 makes the insulation effectively continuous.

A secondary winding 32 is then wound over the insulation layer 30; but it will be observed that the layer 30 and insulator 12 co-operate to insulate from one another the windings 28 and 32, the insulator' 12 blocking the difficultly-insulatab'le end-portions 26 of winding 28 from the winding 32, by an insulating means which readily and economically withstands the subsequent winding process or processes. Nothing can even get to the wire-portions 26 to scrape them to permit a shortage across to the winding 32; and the dielectric nature of the insulator 12 and insulation layer 30 can be suflicient to prevent any areing across between the windings and all portions thereof.

A second insulator 12 (not shown), which may be and desirably is identical to the insulator 12, may be used if a thirdwinding is to be used; and in this situation, the radially-extending end-portions 34 of the secondary windings 32 will be passed between that second insulator 12 (not shown) and the insulator 12 shown.

Similarly, it will be seen that the number of insulators 12 to be used on any transformer would be desirably of a quantity which is one less than the number of windings.

It should be noted that the wire routinely used in winding transformers is of a type which is insulated by a coating which is applied onto the wire in only a very thin layer, of dielectric amount and character generally only that to rather eflectively insulate wires of substantially the same voltage or potential. Thus it is seen that the problem of shortage by a scrape in the insulation is particularly significant in locations where Wires of two different windings of the transformer are adjacent; and it is that type of insulating-situation to which this invention is directed, and whose insulation problems are economically and effectively solved by this invention.

It is thus seen that an insulated transformer according to concepts of the present invention provides novel and advantageous concepts and features, providing a transformer having insulation means which are desirable.

Accordingly, it will thus be seen from the foregoing description of the invention according to this illustrative embodiment, considered with the accompanying drawings, that the present invention provides a new and useful device having desired advantages and characteristics, and accomplishing its intended objects, including those hereinbefore pointed out and others which are inherent in the invention.

Modifications and variations may be effected without departing from the scope of the novel concepts of the invention; accordingly, the invention is not limited to the specific form or arrangement of parts herein described or shown. For example, although the winding spindle .14 is referred to as a tube, it is not necessary for the purpose of this invention that it be hollow; and, similarly, it is not necessary for the purpose of this invention that it'be of square cross-section.

What is claimed is:

1. In an electrical transformer having a winding tube around which are wound at least two generally co-axial windings of wire:

a non integral flange member retained onto said winding tube at the side of the relatively inner one of said windings;

means permitting a portion of said winding wire at the side of said winding to be passed past the said flange member;

the said flange member providing a shielding means maintaining the said portion of said winding wire in a shielded location with respect to the space occupied by the relatively outer one of said windings;

the arrangement being such that the said winding wire passes the said flange member at a radial distance from the axis of said winding at least substantially as small as the outer portion of said winding and thereby provide that none of the winding portion which is disposed on the winding side of said flange will be disposed significantly radially outwardly of said winding in a radially-outward position in which its insulation-preservation will be significantly more a problem than that of the outermost portion of the winding itself.

2. The invention as set forth in claim 1 in a combination in which the said flange member is a sheet-like panel member having an opening which both provides a means for inserting it onto said winding tube, the opening being of such a size and shape in comparison to the said winding tube that the panel member must be slightly deformed to effect the insertion of the panel member onto said tube, and provides an accommodation opening in the flange member to permit the winding wire to be passed through said opening to the said small radial distance location.

3. The invention as set forth in claim 2 in a combination in which the said flange member is a generally C-shaped piece the arms of which are adapted to embrace the winding tube as above specified, and the opening between the ends of the arms provides the said opening.

4. The invention as set forth in claim 1 in a combination in which the said flange member is a generally C- shaped piece, the arms of which are adapted to embrace the winding tube, and the opening between the ends of the arms provides the access permitting the wire to be passed through said opening to the said small radial-distance location.

5. The invention as set forth in claim 4 in a combination in which the fit between the said flange-member arms and the winding tube and the wire-portion passing the said flange member is snug and maintains the flange member at a located position along said tube.

6. The invention as set forth in claim 4 in a combination in which the ends of the arms are spaced apart a distance less than the operative diameter of the winding tube thereby assisting in the retaining of said flange member onto said winding tube.

7. The invention as set forth in claim 1 in a combination in which the said flange member is a generally C-shaped piece adapted to be inserted onto the winding tube by moving it in a direction transverse to the axis of the winding tube and thus into operative association with said winding tube after the end flanges of the tube are aflixed onto the said winding tube.

8. The invention as set forth in claim 7 in .a combination in which the said flange member is formed so that it must be resiliently deformed to be inserted onto the said winding tube.

9. The invention as set forth in claim 7 in a combination in which there is a snug fit between the flange member and the winding tube and the wire-portion passing the flange member, thereby maintaining the flange member at a located position along said tube.

' 10. The invention as set forth in claim 1 in a combination in which there are provided a plurality of said flange members in a quantity at least one less than the number of the generally co-axial windings of wire.

References Cited UNITED STATES PATENTS 1/1907 Walsh 336-192 9/1965 Harrison ..336-192 

